#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

/*******found*********/
int fac(int n)
{
	int i;
	int t = 1;
	for (i = 1; i <= n; i++)
		t = t * i;
	/*********found********/
	return t;
}

int main()
{
	int m, n, t, cmn;
	printf("please enter m and n:");
	scanf("%d%d", &m, &n);
	if (m < n)
	{
		t = m; m = n; n = t;
	}
	if (m < 0 || n < 0)
	{
		printf("input error!");
		return 0;
	}
	/*******found*******/
	cmn = fac(m)/fac(n)/fac(m-n);
	printf("C(%d,%d)=%d\n", m, n, cmn);

	return 0;
}